


secrets of the deep

by alexanderlightweight



Series: Words of October 2019 [20]
Category: Shadowhunters (TV)
Genre: Alternate Universe - Canon Divergence, Fluff and Humor, M/M, Semi-Sentient Tentacles, Sirens, Tentacles, Tentacletober
Language: English
Status: Completed
Published: 2019-10-12
Updated: 2019-10-12
Packaged: 2020-12-09 18:24:43
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,372
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20999312
Author URL: https://archiveofourown.org/users/alexanderlightweight/pseuds/alexanderlightweight
Summary: Trying to date when you're a siren and your boyfriend is a warlock from Brooklyn isn't always easy.  Thankfully magic is very helpful when trying to complicate a relationship.Yes.That says complicate.





	secrets of the deep

**Author's Note:**

  * For [lynne_monstr](https://archiveofourown.org/users/lynne_monstr/gifts).

> I was trying to figure out what to write for prompt: surprise tentacles! and then I was thinking about the differences in tentacles and remembered some old info and then threw myself into a research binge and well, surprise! this happened.

“Alexander!” 

Alec flipped over from where he’d been floating on his back, excitement filling him at the sound of Magnus’ voice. It had been nearly a week since he’d seen his lover and fire-messages just weren’t the same as seeing him in person.

They also didn’t always work, seeing as Alec lived in a very non-fire friendly zone.

“Magnus, over here!” He yelled back and slapped his tail against the surface of the ocean, letting the noise echo around their cove.

“Hello darling,” Magnus said once he’d cleared the small wall of rocks separating the cove from the outer beach and around Alec the water was rippling with his excitement. “I’ll join you in just a minute, alright?” 

Alec nodded, watching as Magnus put down his bag and then casually stripped off his clothes before taking out a small glass vial and downing it. Alec was about to swim to him when he paused, watching as blue magic started to surround Magnus from head to toe as he stepped into the ocean, lighting the water up and when it dimmed, there was a dark mass where Magnus’ legs should have been.

“What… are those?” Alec asked, watching warily as one of the dark tendrils uncurled and reached out. He allowed it, as curious as he was concerned and froze when it curled snugly around his arm.

“I decided to surprise you, darling. I finally figured out how to temporarily transform so I can join you for a change.”

Alec felt the little fins along his spine shudder and his tail swished without thought, pushing him a little further away from Magnus but the tentacle kept him from going too far.

“Really?” He asked, eyes focused on the dark tentacles. There were definitely more than just eight and they would be hard to see without magic in the unlit chasms of the ocean. 

“Alexander?” 

Alec was brought from his thoughts by Magnus gracefully approaching him, another tentacle reaching out. “Magnus,” Alec said warningly, “one is more than enough.”

“What on earth is wrong? I thought you’d be happy, I know the transformation from tail to legs is hard for you to do so often.” Magnus looked concerned but also a little putout and Alec knew he’d probably exhausted himself while figuring this out. 

“I’m fine, it’s just,” he paused trying to relax, “it’s just instinct Magnus.” He tried to give his lover a small smile but by the frown on Magnus’ face he doubted that he’d succeeded. 

“So you hate it.”

“It’s not that simple, you’re gorgeous. Really,” Alec said quickly and even swam a little closer, not too close, but closer.

“Alexander, if I could have figured out how to gain a tail I would have. However, as we learned from your transformations, for some reason it’s easier to fuse one part of someone into many parts. I don’t know why, but it is.” Magnus was sounding distressed now and Alec swallowed back both his instincts and the warning voice in the back of his head and swam closer still.

“There you are,” Magnus said and when he reached out a hand, Alec took it, trying not to shudder when yet another tentacle brushed his tail. “Are you hurt?

“No,” Alec said and tried to focus on Magnus’ smile, “I’m fine.”

“You’re so skittish darling, I thought maybe you were hiding another injury or something.” Magnus pulled him closer and as he did, all of his tentacles moved with him,  _ towards _ Alec.

“Magnus, listen I will love you,  _ all _ of you always.” Alec promised fervently, “but, well-”

“Just not if I have tentacles?” Magnus asked somewhat incredulously, “Alexander, you’re a siren and the ocean is your home. If anything I thought this would be  _ more _ attractive to you?” 

“Only if I wanted to be eaten!” Alec retorted and immediately regretted it when Magnus’ eyes gleamed slyly and his tentacles reached out, coiling around him.

“Oh, do you want me to play predator, Alexander?” 

Alec wanted to laugh but he was frozen, hyper-focused on the tentacles that were wrapping almost devoutly around his tail. They weren’t squeezing or latching on but Alec could feel his heart racing and he had the feeling Magnus could too because he paused. 

“Alec, sweetheart are they really that bad?” 

Alec clung too Magnus’ shoulders, digging his nails in probably a little too deep and tight. “No,” he said and he gritted his teeth, “it’s just. Hard.” 

“Well, something could be,” Magnus muttered and Alec snorted, actually somewhat relaxed by the innuendo. “I really didn’t think you’d be this upset or I would have talked to you first. I just thought that well, something like octopus tentacles didn't seem too far of a stretch to try and-”

“Magnus, you don’t have octopus tentacles,” Alec said and pressed his face to Magnus’ collarbone, breathing in the scent of dirt and trees and asphalt, “you have  _ squid _ tentacles. Giant squid tentacles.”

“Oh, what’s the difference?”

“The difference is that giant squid can and  _ will _ eat us and,” Alec said and shuddered again, “and because of that you need to be  _ very _ careful with those. They’ll leave a mark.”

“Oh? I thought you like it when I left marks.” 

Magnus was very clearly trying to lighten the mood but Alec leveled him with an unimpressed glare, “well that was before you gained thousands of extra teeth.”

“What?”

“All of those,” Alec pointed his chin towards a nearby tentacle and leaned away when it came over to touch his face, “have little teeth like serrations in the rings. They hook into our skin and drag us down, it’s one of the many reasons why giant squid are so dangerous to us.”

Magnus blinked rapidly and suddenly all of his tentacles made a rather hasty and gentle retreat from Alec’s body, “so if I were to perfect this transformation with say, a different kind of tentacle?”

“Much safer,” Alec said in relief, “that’d be fine. Love it,” he promised, “love  _ you _ , with legs or with tentacles or whatever, just maybe not these kind.”

“I’ll do that then,” Magnus assured and leaned forward to kiss Alec gently on his cheek. Alec allowed the brief peck and then swam backwards, just enough that he was a decent range away.

“So, how long until those go away?” He asked, cautiously watching the mass of pretty but dangerous tentacles. “Because I love you and want to kiss you but I’m also very good with waiting, from over here.”

“No need to wait,” Magnus said and he was staring down at his appendages with a frown, “I infused them all with transformative magic so they have a bit of a mind of their own. Ah, there we go,” he turned, holding one of his tentacles in his hands and poking at its suckers. “Much better, you’re right I didn’t even realize painful those could have been.” 

Alec grimaced, watching intently as the hard grey of the suckers became a rippling golden ring against the black tentacle. 

“So,” he asked, still keeping his distance, “did it work?” 

“Yes,” Magnus said distractedly, still prodding his own tentacles, “honestly, teeth on somethings limbs. Every time you explain more to me about ocean life I just worry about you more-” and Alec couldn’t wait, crossing the water in a flash and looping his arms around Magnus’ neck happily. “Hello,” Magnus said with a soft, surprised laugh, “now here’s how I thought this would go from the start.”

“We can fix that now,” Alec promised and happily leaned in for a kiss, “I’m not worried about you accidentally ripping me apart any more.” 

Magnus laughed against his mouth, waiting until they’d parted to gaze at him fondly, “I’m glad that’s fixed then.” 

Several of his not harmless -but at least not deadly- tentacles revealed themselves at his words. Alec allowed their approach and watched as they settled on his skin. He allowed their curiosity for a moment, feeling their delicate suckers settle into place on his skin and then nodding his approval.

“No teeth,” he said and he leaned forward for another kiss, “much better.” 

Magnus laughter tasted like magic and salt and happiness and the bubbly drink he sometimes summoned for them.

**Author's Note:**

> I'm on tumblr as [alexanderlightweight](https://alexanderlightweight.tumblr.com)


End file.
